2011 Salinity Summit

Contributions to Permeation Resistance in a VSEP RO System Treating Brackish Water or Brine

Mark Benjamin and Wei Shi

Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195

Reverse Osmosis (RO)

Reverse Osmosis (RO): Increasingly used in treatment of brackish water and brine for potable water

Fouling: Production

Time

Pressure

Time

Constant Pressure Constant Production

VSEP

Vibratory Shear Enhanced Processing

Source: New Logic Research Inc. Emeryville, CA

Shear

VSEP Applications

Landfill Leachate Manure Management Mining Petroleum Processing Pulp and Paper Desalination

VSEP Operation

Concentrate

Feed

Pump

Feed tank

Amplitude: 13°

Frequency: 55Hz

TMP: 140 psi

RO Feed Composition

Brackish water*

Brine: 10 times as concentrated

pH 8.0 Cl 175

Ca 275 as CaCO3 Ba 25

Mg 100 as CaCO3 Si 5

SO4 350 Fe 0.5

Na 175 Alk 150 as CaCO3

TDS 1050

* All units in mg/L, except for pH

Permeate FluxBrackish solution

0

10

20

30

40

50

0.0 0.2 0.4 0.6 0.8 1.0

Recovery

Flu

x (L

/m2-h

)

w/ vibrationw/o vibration

Permeate Flux

Brine

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0

5

10

15

20

25w/o vibrationw/ vibration

Recovery

Flu

x (

L/m

2-h

)

Resistance Breakdown

Rm

RTOT

Rπ

RFRF

= RTOT –Rm –RCP–Rπ

RCP

Contributions to Resistance

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0

10000000000000

20000000000000

30000000000000

40000000000000

50000000000000Membrane

Osmotic P

Fouling

CP

Total

Recovery

Re

sis

tan

ce

(m

-1)

w/ w/o vibrationBrackish solution

inlet outlet

S1S2S3S4

w/o Vibration

w/ Vibration

Higher Shear

Painted Membrane Tests

Shaded Area

Ring for permeation

5.0

5.1

2,

22Re

2

F

R

Ar

h

rravg

(Jaffrin et al. 2002)

r

A

0 100 200 300 400 5000.0

0.2

0.4

0.6

0.8

1.0

5, 0.6410, 0.32 5, 1.2710, 0.6413, 0.9510, 1.2710, 1.5913, 1.27

Specific Volume (L/m2)

Re

lati

ve

Flu

x (

J/J

0)

R, A

Painted Membrane Tests

Painted Membrane Tests

9.0 9.4 9.8 10.2 10.6 11.0-1.0

-0.8

-0.6

-0.4

-0.2

0.0

f(x) = 0.378849919316468 x − 4.28982761861908R² = 0.96729281987083

ln(γ)

ln(J

/J0

)

0.380/ 0.137 WJ J

Mechanisms to Generate Shear

Membrane Rotation

Ultrasound

Longitudinal Vibration

Shear- fouling relationship

Torsional Vibration

Conclusions

Membrane vibration Increases permeate flux Reduces the contribution of fouling

to the total resistance Changes scale morphology into

more porous structures

Shear Rate Governs fouling of RO

membranes Facilitate the design of similar

systems for fouling prevention/reduction

Acknowledgements

This work was supported by the Water Research Foundation (WRF) *.

The authors thank New Logic Research, Inc., for providing the test unit.

Yujung Chang and Pierre Kwan of HDR, Inc., and Sommer Carter of NLR provided valuable technical assistance during the project.

*The views expressed are those of the authors and do not necessarily reflect those of WRF.

RO Membranes

inlet outlet

0.9 cm

10.0 cm

10.24 cm

Membrane BW-30 FE

MWCO (da) 50 30

MaterialPolyamid

ePolyamid

e

pH 1-12 2-11

Tmax (oC) 70 60

Cl2 Tolerance (mg/L)

<0.1 <0.1

Flux*(L/m2‑h)

71 90

Vendor Filmtec Saehan

*At a TMP of 2068 kPa

Solute Rejections

Brackish solution

Brine

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0

200

400

600

800

1000

0

2000

4000

6000

8000

10000Permeate, w/o vibration

Permeate, w/ vibration

Feed, w/o vibration

Feed, w/ vibration

Recovery

Co

nd

uc

tiv

ity

(u

S/c

m)

Co

nd

uc

tiv

ity

(u

S)

Mg Ca Na Si Cl SO450

60

70

80

90

100 w/o vibration

w/ vibration

Re

jec

tio

n (

%)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0

600

1200

1800

2400

3000

0

20000

40000

60000

80000Permeate, w/o vibraitonPermeate, w/ vibrationFeed, w/o vibrationFeed, w/ vibration

Recovery

Co

nd

uc

tiv

ity

(u

S/c

m)

Co

nd

uc

tiv

ity

(u

S)

Mg Ca Na Si Cl SO450

60

70

80

90

100 w/o vibration

w/ vibration

Re

jec

tio

n (

%)

Solid Precipitation

EDAX spectrum of scales on the membrane surface

Gypsum

Aragonite

Solid Precipitation - XRD XRD spectrum of precipitates in the feed solution